The present invention relates to ball screws, and more particularly to an automatic pressure device for a ball screw.
The use of ball screws for positioning workpieces and the like in precision and numerically controlled machine tools and other linear positioning devices is well known. While the high strength and durability of ball screws make them highly desireable for use in these applications, excessive play and backlash can reduce their accuracy in precision positioning.
In a conventional ball screw, play is reduced by inserting a ring or cushion between adjacent ball nuts, causing balls of the respective ball nuts to bear on opposite walls of a spiral groove in a ball screw shaft. While this is effective in reducing shaft play, the heat generated by the resulting constant friction between the balls and the groove walls of the rotating shaft expands components of the ball screw, degrading precision operation.